Apparatus and Method For Tunable Frequency Parametric Down-Conversion Of High Peak Power Lasers Through Dual Chirp Pulse Mixing

ABSTRACT

A laser architecture for selectively producing short high-energy laser pulses having octave-spanning, continuous tunability. Two oppositely chirped pulses are used in combination with a pair of tunable pulse stretcher/compressors to produce a short, high-energy, tunable, broadband pulse.

CROSS-REFERENCE

This Application is a Nonprovisional of and claims the benefit ofpriority under 35 U.S.C. § 119 based on U.S. Provisional PatentApplication No. 62/750,845 filed on Oct. 26, 2018. The ProvisionalApplication and all references cited herein are hereby incorporated byreference into the present disclosure in their entirety.

FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

The United States Government has ownership rights in this invention.Licensing inquiries may be directed to Office of Technology Transfer, USNaval Research Laboratory, Code 1004, Washington, D.C. 20375, USA;+1.202.767.7230; techtran@nrl.navy.mil, referencing Navy Case # 108181.

TECHNICAL FIELD

The present invention provides a high efficiency, tunable,high-contrast, broad-bandwidth laser amplifier with carrier envelopephase locking that can enable the generation of short high-power laserpulses at wavelengths where appropriate gain materials do not exist.

BACKGROUND

High-peak-power lasers are the driving technology behind fields such aslaser machining, fs-chemistry, and next generation particle acceleratorsand light sources to name a few. While many areas require specificoperational wavelengths, to for instance excite a material resonance,existing lasing materials only operate at specific wavelength, limitingutility. The added requirements for certain applications of highrepetition rates, and thus high average powers introduces furthertechnical challenges.

It often is desirable to convert an initial laser pulse having aninitial frequency, initial power, and initial temporal duration into apulse having one or more of a higher energy, a different wavelength, ora different temporal duration.

One method known in the art for doing do converts the initial pulseusing a nonlinear material in a method known as optical parametricamplification (OPA). See M. Ghotbi, V. Petrov and F. Noack, “Generationof tunable, ultrashort pulses in the near-IR with an OPA system based onBIBO,” CLEO/QELS: 2010 Laser Science to Photonic Applications, pp. 1-2.San Jose, Calif., (2010); and A. P. Piskarskas, A. P. Stabinis and V.Pyragaite, “Ultrabroad Bandwidth of Optical Parametric Amplifiers,” inIEEE Journal of Quantum Electronics, vol. 46, no. 7, pp. 1031-1038,(2010); see also EP 2924500 B1 to EKSPLA entitled “Method for generationof femtosecond light pulses, and laser source thereof.”

The block schematic shown in FIG. 1 illustrates aspects of this OPAprocess. As shown in FIG. 1, in OPA, an initial signal pulse having afrequency ω_(s) and a pump pulse having a frequency ω_(p) are input intoa second-order nonlinear crystal NC, where the signal pulse is amplifiedunder a difference frequency or optical parametric amplificationarrangement. The signal pulse and pump pulses combine in the nonlinearcrystal NC to produce an idler pulse having a frequency ω_(i) such thatω_(p)=ω_(s)+ω_(i) and ω_(s)>ω_(i). In addition, beam energy from thepump pulse amplifies the initial signal pulse so as to produce anamplified signal pulse having the same frequency as the initial signalpulse but additional energy provided by the pump pulse. The idler pulse,the amplified signal pulse, and the pump pulse (which, per theprinciples of energy conservation, now has lower energy than it hadbefore) are then output from the nonlinear crystal NC. Thus, because thefrequency of the idler pulse depends on the frequency of both the signalpulse and the pump pulse, by tuning the pump pulse, a desired idlerpulse can be produced from a given signal pulse.

In this scheme, the high peak powers require large beam sizes to keepintensities below the nonlinear material's damage threshold.Additionally, short propagation distances are necessary to maintainphase matching and prevent walk-off. These two requirements can bedifficult or impossible to meet either from a mechanical or materialgrowth point of view.

Another method for converting an initial optical pulse having an initialfrequency, initial power, and initial temporal duration uses ahigh-energy, long pulse narrowband laser to amplify a low-energybroadband pulse though an optical parametric chirped pulse amplification(OP-CPA) scheme. See D. Strickland and G. Mourou, “Compression ofamplified chirped optical pulses”, Opt. Commun. 56, 219 (1985); and I.N. Ross, P. Matousek, M. Towrie, A. J. Langley, and J. L. Collier, Theprospects for ultrashort pulse duration and ultrahigh intensity usingoptical parametric chirped pulse amplifiers, Optics Communications 144,Issues 1-3 (1997); see also U.S. Pat. No. 5,400,350 to Galvanauskasentitled “Method and Apparatus for Generating High Energy UltrashortPulses.”

The block schematic in FIG. 2 illustrates aspects of an exemplaryimplementation of this OP-CPA scheme. As illustrated in FIG. 2, in sucha scheme, a short, low-energy broadband signal pulse, typically having apulse duration of about 100 fs, is input into a positive pulsestretcher, which lengthens the temporal duration of the pulse by aboutthree orders of magnitude, or to about 100 ps. Once the initial signalpulse has been so stretched, the signal is combined with a high energynarrowband pump pulse, often having a pulse duration of about 1 ns, andboth pulses are input into a nonlinear crystal (NC). As in the OPAscheme illustrated in FIG. 1, the signal pulse and pump pulses combinein the nonlinear crystal NC to produce an idler pulse and an amplifiedsignal pulse as described above. The amplified signal pulse is theninput into a negative compressor, which shortens the pulse duration fromits stretched duration of about 100 ps to a compressed duration of about100 fs to produce a final short high-energy pulse that is output fromthe pulse amplifier system. The idler pulse and any remaining energyfrom the pump pulse is removed from amplifier system and their energy isabsorbed by an optical beam dump.

In this OP-CPA scheme, the short low-energy broadband pulse istemporally stretched through the addition of a linear chirp by a pulsestretcher. This long, chirped pulse is then mixed with and amplified bya long high energy pump pulse in a nonlinear material. The linear chirpis then removed by a pulse compressor producing a final short highenergy pulse. Formation of the long pulse reduces beam intensities andthus the demands placed on the nonlinear amplifier material. However,the nonlinear mixing process reduces the bandwidth of the pulse, thusincreasing the minimum achievable pulse length. Additionally, since thepulses are generated separately, there is typically no tunability in thegenerated pulse and no straightforward way to achieve carrier-envelopephase (CEP) locking. See Ferenc Krausz and Misha Ivanov, “AttosecondPhysics,” Rev. Mod. Phys. 81, 163 (2009).

Yet another method for generating a high-energy laser pulse usesdual-chirped optical parametric amplification (DC-OPA). In this method,a pump pulse having a positive chirp and a seed pulse having a negativechirp are mixed to produce an idler pulse with a positive chirp. Thechirp is then removed from the idler producing an even shorter pulse.See Qingbin Zhang et al., “Dual-chirped optical parametric amplificationfor generating few hundred mJ infrared pulses,” Optics Express, Vol. 19,No. 8, pp. 7190-7212 (2011); see also Yuxi Fu et al., “Generation of a200-mJ class infrared femtosecond laser by dual-chirped opticalparametric amplification,” Conference on Lasers and Electro-Optics, OSATechnical Digest (online) (Optical Society of America, 2017), paperSM3I.3; Yuxi Fu et al., “Towards a petawatt-class few-cycle infraredlaser system via dual-chirped optical parametric amplification,”Scientific Reports 8, Article number: 7692 (2018); and Yuxi Fu et al.,“Generation of high-energy mid-infrared pulses at 3.3 μm by dual-chirpedoptical parametric amplification,” Conference on Lasers andElectro-Optics, OSA Technical Digest (online) (Optical Society ofAmerica, 2018), paper SF1N.5. Other methods produce use chirped pulseamplification to amplify negatively and positively chirped pulses. SeeM. P. Kalashnikov, K. Osvay, I. M. Lachko, H. Schonnagel and W. Sandner,“Broadband amplification of 800-nm pulses with a combination ofnegatively and positively chirped pulse amplification,” in IEEE Journalof Selected Topics in Quantum Electronics, vol. 12, no. 2, pp. 194-200,(2006).

SUMMARY

This summary is intended to introduce, in simplified form, a selectionof concepts that are further described in the Detailed Description. Thissummary is not intended to identify key or essential features of theclaimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter. Instead, it ismerely presented as a brief overview of the subject matter described andclaimed herein.

The present invention provides a new laser architecture, known as DualChirp Optical Parametric Chirped Pulse Amplification (DC-OPCPA), forselectively producing short high-energy laser pulses havingoctave-spanning, continuous tunability. Unlike the prior art techniquesfor pulse amplification discussed above, in accordance with the presentinvention, two oppositely chirped pulses are used in combination with apair of the novel tunable pulse stretcher/compressors of the presentinvention to produce a short, high-energy, tunable, broadband pulse.

The envisioned mode of operation is that for signal amplification that apositive chirp is applied, the signal is amplified and thenrecompressed. For idler amplification, a negative chirp is applied tothe signal, that generates an amplified positively chirped idler, andthen the idler is compressed.

A tunable DC-OPCPA system in accordance with the present inventionrequires (1) a broad-bandwidth, ultrashort seed pulse and (2) a tunablepulse stretcher and compressor to access the various operationalwavelengths. The seed pulse can be provided by means of supercontinuumgeneration, wherein a small portion of an initial high energy broadbandpump pulse can be compressed to generate a low energy ultrashort pulse.This ultrashort pulse can be focused into a material (e.g., fusedsilica) and through strong self-phase modulation generates anultrabroadband (white light) source extending over the range ofwavelengths over which the DC-OPCPA can be tuned. The desiredoperational wavelength can then be selected from this white lightsource.

In order to amplify the ultrashort pulses to high energy, they need tofirst be stretched temporally, amplified, and then recompressed. Thisgeneral process is known as chirped pulse amplification (CPA). Toaccommodate a changing operational wavelength, both the stretcher andcompressor needs to be tunable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block schematic illustrating aspects of optical pumpamplification (OPA) of a source laser pulse in accordance with the priorart.

FIG. 2 is a block schematic illustrating aspects of optical parametricchirped pulse amplification (OP-CPA) of a source laser pulse inaccordance with the prior art.

FIGS. 3A and 3B are block schematics illustrating aspects of aDual-Chirp Optical Parametric Chirped Pulse Amplification (DC-OPCPA)system for amplification of a source laser pulse in accordance with thepresent invention.

FIG. 4 is a block schematic illustrating aspects of a tunable pulsestretcher used in a DC-OPCPA system in accordance with the presentinvention.

FIG. 5 is a block schematic further illustrating aspects of a tunablepulse stretcher used in a DC-OPCPA system in accordance with the presentinvention.

FIG. 6 is a block schematic further illustrating aspects of a tunablepulse compressor used in a DC-OPCPA system in accordance with thepresent invention.

FIGS. 7A and 7B are plots showing the results of a simulation of pulseamplification and compression using dual-chirp optical pulseamplification (DC-OPCPA) in accordance with the present invention.

DETAILED DESCRIPTION

The aspects and features of the present invention summarized above canbe embodied in various forms. The following description shows, by way ofillustration, combinations and configurations in which the aspects andfeatures can be put into practice. It is understood that the describedaspects, features, and/or embodiments are merely examples, and that oneskilled in the art may utilize other aspects, features, and/orembodiments or make structural and functional modifications withoutdeparting from the scope of the present disclosure.

The present invention provides a high efficiency, tunable,high-contrast, broad-bandwidth laser amplifier with carrier envelopephase locking that can enable the generation of short high-power laserpulses at wavelengths where appropriate gain materials do not exist.

The laser amplifier scheme of the present invention, Dual Chirp OpticalParametric

Chirped Pulse Amplification (DC-OPCPA), utilizes a high-energy, chirpedpulse as a pump to amplify lower frequency, broadband pulses within anonlinear crystal. The amplification is done within a second-ordernonlinear material under difference frequency generation or opticalparametric amplification arrangements known in the art. However, asdescribed in more detail below, the use of a single initial pulse toproduce oppositely signed chirped pump and signal pulses is a newfeature of the DC-OPCPA scheme in accordance with the present invention,and leads to the generation of an idler pulse having increased bandwidthfrom the initial signal pulse, where the idler pulse which enablespassive carrier envelope phase (CEP) locking. For a positively chirpedpump and negatively chirped signal, a positively chirped idler pulse isproduced that can be compressed using standard dispersive opticalelements. In addition, as described in more detail below, the laseramplifier scheme in accordance with the present invention furtherincludes a novel tunable pulse stretcher/compressor that enables thelength of the pulse to be tuned over the transmission region of thenonlinear second-order material. This is achieved by allowing both thestretcher/compressor systems to be designed to allow for both rotationand changes in the grating separation.

The present invention provides a new laser architecture for selectivelyproducing short high-energy laser pulses having octave-spanning,continuous tunability. Unlike the prior art techniques for pulseamplification discussed above, in accordance with the present invention,two oppositely chirped pulses are used in combination with a pair of thenovel tunable pulse stretcher/compressors of the present invention toproduce a short, high-energy, tunable, broadband pulse.

The envisioned mode of operation is that for signal amplification that apositive chirp is applied, the signal is amplified and thenrecompressed. For idler amplification, a negative chirp is applied tothe signal, that generates an amplified positively chirped idler, andthen the idler is compressed.

A tunable DC-OPCPA system in accordance with the present inventionrequires (1) a broad-bandwidth, ultrashort seed pulse and (2) a tunablepulse stretcher and compressor to access the various operationalwavelengths. The seed pulse can be provided by means of supercontinuumgeneration, wherein a small portion of an initial high energy broadbandpump pulse can be compressed to generate a low energy ultrashort pulse.This ultrashort pulse can be focused into a material (e.g., fusedsilica) and through strong self-phase modulation generates anultrabroadband (white light) source extending over the range ofwavelengths over which the DC-OPCPA can be tuned. The desiredoperational wavelength can then be selected from this white lightsource.

In order to amplify the ultrashort pulses to high energy, they need tofirst be stretched temporally, amplified, and then recompressed. Thisgeneral process is known as chirped pulse amplification (CPA). Toaccommodate a changing operational wavelength, both the stretcher andcompressor needs to be tunable.

The block schematics in FIGS. 3A and 3B illustrate aspects of the novellaser architecture and method for selectively producing shorthigh-energy laser pulses in accordance with the present invention.

As illustrated in FIGS. 3A and 3B, the laser architecture used in themethod of the present invention includes a high-energy broadband lasersource 301, a white light continuum optical parametric amplifier (WLCOPA) 304, a tunable stretcher 306, a dual-chip optical parametricamplifier (DC OPA) 308, and a tunable compressor 310.

As illustrated in FIGS. 3A and 3B, broadband laser source 301 emits ahigh-energy broadband pump pulse 302 having a frequency 1070 _(p) and apulse length on the order of about 100 to about 200 ps. In the exemplarycase described herein pulse 302 is positively chirped, but the methodand apparatus in accordance with the present invention can also processa negatively chirped pulse in a manner comparable to that describedherein. In accordance with the present invention, a small portion of theenergy from this pulse is split off and is then compressed and used togenerate a white light continuum (WLC). WLC is a nonlinear process wherea short pulse is propagated through a material (e.g., fused silica)where it undergoes strong self-phase modulation. This leads tosignificant enhancement of the pulse's spectral bandwidth, producing thewavelengths necessary to seed the amplifier system. The WLC processproduces a seed pulse referred to herein as signal pulse 303, having afrequency ω_(s) and a pulse length on the order of about 10 fs. SeeJiun-Cheng Wang and Juen-Kai Wang, “Experimental and theoreticalanalysis of white-light seeded, collinear phase-matching, femtosecondoptical parametric amplifiers,” J. Opt. Soc. Am. B 21, 45-56 (2004).Signal pulse 303 can be used as is, or it can be further amplifiedthrough OPA 304 to produce an amplified signal (idler) (s+i) pulse 305having both the original signal pulse energy plus a small amount ofidler energy. Signal (idler) pulse 305 is then input into tunable pulsestretcher 306 where is it selectively stretched and chirped to producenegatively chirped signal (idler) pulse 307 having a pulse length on theorder of about 100 ps.

Positively chirped initial pump pulse 302 and negatively chirpedsignal(idler) pulse 307 are then directed into dual-chirp opticalparametric amplifier (DC-OPA) 308 which contains the novel tunablestretcher/compressor described below, that can actively adjust allowingfor operation at varying wavelengths. Both the signal and idler areamplified in DC-OPA 308 until the pump energy begins to deplete, withthe signal and idler mixing to produce a high-energy, positively chirpedidler(signal) pulse 309 having a frequency ω_(i)=ω_(p)−ω_(s) and a pulselength on the order of about 100 ps. This idler pulse has a spectralbandwidth that is greater than that of both the pump and the signal, andfurther has a pulse-to-pulse stable carrier envelope phase (CEP) offsetbecause both the pump and signal arise from a single pulse and thereforehave a fixed phase difference.

Pulse 309 is then directed into tunable compressor 310, where it iscompressed to produce the final short, compressed high-energy pulse 311having a pulse length on the order of about 10 fs, while the residualenergy from the pump pulse 302 and signal(idler) pulse 307 are outputinto energy dump 312.

As noted above, this short high-energy pulse is generated from theinitial longer, lower-energy pulse through the use of a pair of noveltunable pulse stretcher/compressors in accordance with the presentinvention that can selectively operate at varying wavelengths.

The block schematic in FIG. 4 illustrates aspects of the novel tunablepulse stretcher/compressor in accordance with the present invention.

In the exemplary embodiment illustrated in FIG. 4, a tunablepulse/stretcher in accordance with the present invention incorporates atwo-grating pulse stretcher, but other dispersion based stretchers suchas prism-based or multi-grating stretcher could also be used.

Thus, as illustrated in FIG. 4, in an exemplary embodiment, two gratings410 and 420 are used to spatially disperse and collimate the frequencycontent of an incoming broadband pulse 401. Thus, as illustrated in FIG.4, incoming pulse 401 is reflected from grating 410 and is fanned outinto a continuous spectrum having multiple frequency components such asfrequency components 402 a and 403 a, which are reflected from grating410 at different angles relative to the grating. Frequency components402 a and 403 a reflect off grating 420 such that they travel in aparallel path, shown in FIG. 4 by lines 402 b/403 b. Grating 410 directsfrequencies 402 b/403 b to retroreflector 430, which reflects the pulsesback into grating 420 as frequency components 402 c/403 c. Grating 420then reflects frequency components 402 c/403 c back to grating 410 asfrequency components 402 d/403 c. Finally, grating 410 reflectsfrequency components 402 d/403 d onto the same path producing outputpulse 404. The different path lengths traveled by the frequencycomponents 402/403 results in a relative time delay between thefrequency components. For a continuous spectrum, this results in anelongated pulse with a temporal frequency dependence, or “chirp.” Bytuning the angle θ of grating 410 with respect to the initial pulse 401and the separation (d) between gratings in each of gratings 410 and 420,the pulse stretcher/compressor can be selectively tuned to process inputpulses having various wavelengths and to produce output pulses havingpredetermined chirp rates.

The use of such an adjustable pulse stretcher deviates from prior artCPA architectures, and its tunability is key for optimizing the DC-OPCPAprocess in accordance with the present invention. While prior artarchitectures often use a final pulse compressor, such a compressorarchitecture is typically reserved for compression of the final pulsebecause although it can compress high energy pulses, it can onlyintroduce a negative chirp. A positive chirp architecture is morecomplicated, limiting tunability and pulse energy and is thus reservedas the stretcher to compliment the negative chirp architecture for thecompressor. For DC-OPCPA, the required positive chirp for compression isproduced by the nonlinear interaction.

A basic design of the stretcher is further illustrated by the blockschematic shown in FIG. 5.

In the stretcher, the grating angle θ, i.e., the angle of the gratingrelative to the incident pulse, is used to tune the wavelength of thestretched pulse, while the separation L between the grating and thecurved mirror is used to control the chirp. The operational wavelengthis changed by rotating the grating, while the chirp is changed bychanging the separation between the curved mirror and the grating. Inthis arrangement both positive and negative chirps can be applied,however it is not suitable for high energy pulses and thus reserved foras a stretcher. The change in the distance L changes the relative pathlengths traveled by different frequency components, allowing access tovarying chirp rates. In this arrangement, an L less than the focallength of the mirror produces a positive chirp, while an L greater thanthe focal length produces a negative chirp.

The basic compressor design is shown in FIG. 6. The operationalwavelength is changed by rotating the setup about the first grating. Thechirp is adjusted by changing the distance between the first grating andthe second grating/retroreflector pair. In this arrangement onlynegative chirps can be applied, however it can handle high energy pulsesand so can be used for pulse compression. As with the pulse stretcherdescribed above, the angle θ between the input pulse and the firstgrating can be tuned to produce a predetermined wavelength of thecompressed pulse, while the separation L between the first grating andthe second grating can be tuned to control the chirp, wherein anincrease in L leads to an increase in the negative chirp. The wholesetup is rotated about the center axis of the first grating to maintainalignment through the whole system.

EXAMPLES

2-D axisymmetric simulations of pulse generation in accordance with thepresent invention were run with the MATLAB Sandia Nonlinear Optics(mlSNLO) code. The simulation used a positively chirped, 800 nm pump anda negatively chirped, 1500 nm signal in a 7 mm, type I beta bariumborate (BBO) crystal to produce a positively chirped 1714 nm idler andamplified signal pulse. The pump parameters are 2.0 J, 200 ps with 18THz of bandwidth (chirp parameter 0.09 THz/ps), while the signalparameters are 2.4 mJ, 100 ps also with 18 THz of bandwidth (chirpparameter −0.18 THz/ps).

The results of this simulation are shown in FIGS. 7A and 7B.

FIG. 7A is a plot of the normalized spectral power density of the pump(701), signal (702), and idler (703). Depletion of the pump energy canbe observed as a dip in the pump spectrum, and a slight increase inspectrum. While the signal maintains its spectrum, the resulting idlerpulse's spectrum is larger than both the pump and the signal. From thesimulation, the amplified signal is 247 mJ, 100 ps, with 18 THz ofbandwidth (chirp parameter −0.18 THz/ps), while the idler is 214 mJ, 100ps, with 28 THz of bandwidth (chirp parameter 0.28 THz/ps). FIG. 7Bshows the result when the chirp is removed from the idler pulse. Theidler's pulse duration is reduced from 100 ps to 23 fs, shorter thanboth the pump and signal when they are individually compressed.

Simulated runs were also made at other signal wavelengths. The resultingpulse energy for the signal and idler pulses is summarized in Table Ibelow:

TABLE I Signal (nm) Idler (nm) Es (mJ) Ei (mJ) 1500 1714.3 247 214 14001866.6 207 153 1300 2080 139 85.6 1200 2400 50 23.8

The amplified, positive chirped idler is then directed into a simulatedtunable pulse compressor in accordance with the present invention thatcan selectively compress the pulse to provide a predetermined pulsepower and/or pulse duration. Through tuning of the compressor, the CEPof the passively locked idler can be actively tuned. See E. Treacy,“Optical pulse compression with diffraction gratings,” in IEEE Journalof Quantum Electronics, vol. 5, no. 9, pp. 454-458 (1969). Assuming anefficiency of about 70%, CEP pulses having a power of about 10 TW can betunably produced from initial pulses having a wavelength of 1.6-2.6 μm.The same scheme can be applied using a negatively chirped idler pulse toproduce an ˜10 TW tunable signal from initial pulses having a wavelengthof about 1.1-1.6 μm. Either of these pulses can be frequency convertedthrough either harmonic generation or OPA/OPCPA/DC-OPCPA to generatetunable pulses in the visible or mid-wave through long-wave infrared,respectively.

Advantages and New Features

This technique combines the benefits of both OPA and OPCPA technologywith the addition of active CEP control and increased bandwidth thatleads to potentially shorter, transform-limited pulses. In summary,DC-OPCPA produces high-energy, high-contrast pulses with increasedbandwidth at high quantum efficiency allowing operation at high averagepowers. Combined with tunable stretcher/compressors, the system supportstunable, ultrashort pulses, with active CEP management of the idlerpulse without the complication of a CEP controlled pump system. Such anapproach is general and can be adapted to any chirped laser systemoperating at arbitrary wavelengths and repetition rate.

Alternatives

As discussed above, OPA and OPCPA are the only alternatives that do notrely on a lasing material. There are no known lasing materials that canpossibly provide the tunability that this system provides. OPA islimited to lower intensity pulses while OPCPA is limited by seed pulses,reduced bandwidth, and does not provide CEP locking.

In cases where beam quality is a concern, the idler can be firstproduced in a pre-amp, spatially filtered and then used to seed a finalamplifier.

There is no known technique that provides the flexibility of thisapproach for producing high power laser pulses.

The present disclosure describes various particular aspects, embodimentsand features of an architecture and method for producing compressed,high-power laser pulses. Although particular embodiments, aspects, andfeatures have been described and illustrated, one skilled in the artwould readily appreciate that the invention described herein is notlimited to only those embodiments, aspects, and features but alsocontemplates any and all modifications and alternative embodiments thatare within the spirit and scope of the underlying invention describedand claimed herein. The present application contemplates any and allmodifications within the spirit and scope of the underlying inventiondescribed and claimed herein, and all such modifications and alternativeembodiments are deemed to be within the scope and spirit of the presentdisclosure.

What is claimed is:
 1. A method for selectively producing a shorthigh-energy laser pulse having a predetermined wavelength and apredetermined chirp, comprising: directing an initial laser pulse into asplitter, which splits off a portion of energy from the initial pulse toform a first signal pulse, the remaining energy from the initial laserpulse forming a pump pulse; inputting the first signal pulse into atunable pulse stretcher, the tunable pulse stretcher controllablyconverting the first signal pulse into a second signal pulse having apredetermined wavelength and a predetermined positive or negative chirp;inputting the second signal pulse and the pump pulse into a pulseamplifier, the pulse amplifier combining the second signal pulse and thepump pulse into a single amplified pulse; inputting the amplified pulseinto a tunable pulse compressor, the tunable pulse compressorcontrollably converting the amplified pulse into a high energy outputsignal pulse having a predetermined wavelength and a predeterminedpositive chirp.